The long-term objective of this research proposal is to elucidate underlying biological and behavioral mechanisms whereby stressful social and physical environments contribute to health disparities between socioeconomic and racial groups. To achieve this objective, the following Specific Aims are proposed: Aim 1 - To determine whether persons who are caregivers for a spouse with Alzheimer's Disease or other chronic dementia have a more adverse profile of behavioral and biological characteristics than matched controls without caregiving responsibilities. Aim 2 - To determine whether living in a stressful physical environment (based on neighborhood characteristics) leads to a more adverse profile of biobehavioral characteristics among caregivers than noncaregivers. Aim 3 - To determine whether the impact of stressful social and/or physical environments on health-damaging biobehavioral characteristics is moderated by the presence of a hostile personality type or genetic polymorphisms that affect CNS serotonin function. In secondary analyses, we shall also evaluate the moderating effect of other potential moderators - e.g., underlying CHD or other medical disorder, race, gender, social support, and socioeconomic status. We shall recruit a sample of 200 caregivers and 200 matched controls without caregiving responsibilities. We shall assess the impact of caregiver status on behavioral (negative affects and health practices) and biological (cardiovascular and neuroendocrine function at rest and during stress, metabolic syndrome) characteristics likely to underlie health disparities. We shall determine the impact of the physical neighborhood environment, both alone and interacting with caregiver status, upon the biobehavioral mechanisms. We shall also evaluate the moderating effects of serotonin-related genetic polymorphisms, hostile personality type and other medical/physical and social characteristics of the subjects upon the impact of caregiving and physical environments on biobehavioral mechanisms. In addition to increasing understanding of biobehavioral mechanisms responsible for health disparities, the findings could point to targets for specific interventions aimed at ameliorating these disparities.